read-strategy

name	read-strategy
description	Strategy for reading data from CAS or SAS tables. Determines which read tool to use (raw reads vs analytical queries).

Read Table Strategy

Mandatory two-step sequence — never skip or reorder

Step 1 and Step 2 are required for every read request. Step 2 must never run before Step 1 succeeds.

---

Step 1 — Verify the table exists and resolve its server (REQUIRED)

GATE:

Do not check for the existence of the library separately. Follow the workflow below. The sas-score-find-table tool will check for the existence of the table in the specified library and server, which implicitly verifies the library as well.

Workflow to read a table

Step 1 — Verify the table exists and resolve its server (REQUIRED)

1. Call sas-score-find-table({ lib, name: table, server: "cas" })
   • ✅ Found → confirmed lib = lib as given, confirmed server = "cas" → go to Step 2
   • ❌ Not found → call sas-score-find-table({ lib: lib.toUpperCase(), name: table, server: "sas" })
     • ✅ Found → confirmed lib = uppercased lib, confirmed server = "sas" → go to Step 2
     • ❌ Not found in either → stop. Tell the user the table was not found.

Step 2 — Read the table

Use the confirmed lib and server from Step 1. Never guess or default the server.

Use sas-score-read-table for all row reads, including filtered reads with a WHERE clause. Use sas-score-sas-query only when the request requires SQL aggregation (COUNT, SUM, AVG, MIN, MAX), GROUP BY, JOIN, or computed columns. A WHERE clause alone is not a reason to use sas-query.

Read Table (sas-score-read-table)

When: raw rows, filtered rows, browsing — anything that is not an aggregation or join.

Parsing row count from user input:

User says	start	limit
"first N rows/records"	1	N
"top N rows"	1	N
"N rows" / "N records"	1	N
"rows N to M"	N	M−N+1
"starting from row N"	N	10
(not specified)	1	10

"first" always means start at row 1 and return N rows. It is never a row offset.

Dotted format: "lib.table" → lib: "lib", table: "table" (split on first dot).

Parameters: lib, table, server (confirmed from Step 1 — required), start, limit, where

SQL Query (sas-score-sas-query)

When: COUNT/SUM/AVG/MIN/MAX, GROUP BY, JOIN across tables, or computed columns.

NOT for: simple filtered reads — use read-table with where instead.

Parameters: table (as "lib.table"), query, sql

Decision

Does the request need aggregation (COUNT/SUM/AVG/GROUP BY) or a JOIN?
  YES → sas-score-sas-query
  NO  → sas-score-read-table  (pass filter in `where` parameter if needed)

Table Name Format

• CAS: Public.customers, Caslib.table
• SAS: SASHELP.cars, LIBREF.table (uppercase libref)
• Dotted input "x.y" → lib=x, table=y

Error Handling

Error	Action
Table not found	Verify with find-resources first
Empty result	Ask user to adjust WHERE clause
Column not found	Ask user to verify column name (case-sensitive)